In semiconductor device manufacturing, a desired circuit pattern is formed by photolithography that applies a photoresist liquid to a substrate having a predetermined film formed thereon to form a resist film, exposes the resist film with the desired circuit pattern and develops it. More particularly, a wafer as a substrate is subjected to a series of processes including a cleaning process, a dehydration baking process, an adhesion (hydrophobizing) process, a resist coating process, a pre-baking process, an exposure process, a developing process, and a post-baking process.
In a resist coating system that forms a resist film by supplying a photoresist liquid (hereinafter referred simply as “resist”) to a wafer, it sometimes occurs that, a resist adhering to the tip of the resist supplying nozzle after discharging the resist dries and solidifies so as to generate crystals. When the resist is further discharged from the nozzle with the crystals still adhering to the tip thereof, a normal resist discharging operation may not be performed, or the crystals may be supplied onto a wafer together with the resist.
As a countermeasure against the above problem, there has been known a technique that creates an atmosphere of a vapor of a solvent, such as a thinner, around a nozzle in the nozzle standby area, so as to suppress drying and solidifying of the resist adhering to the nozzle tip, thereby preventing generation of crystals.
In order to suppress drying and solidifying of the resist, a solvent vapor atmosphere of a high concentration is required. However, when a nozzle is placed in a solvent vapor atmosphere of a high concentration, dew drops are likely to be formed on the outer circumferential surface of the nozzle. If the dew drops fall on a substrate, processing of the substrate may be adversely affected.
In addition, adhering matters that have already been crystallized cannot be removed by the above method. In order to remove crystals, a nozzle has to be cleaned with the use of a cleaning liquid. JP5-309309A discloses a nozzle cleaning apparatus that may be used for such a purpose (note that the nozzle cleaning apparatus disclosed herein is a nozzle cleaning apparatus that cleans a nozzle for applying a highly viscous fluid such as adhesive, paint, and grease). FIG. 8 schematically shows the nozzle cleaning apparatus disclosed in JP5-309309A. A syringe (ejector) 52 is fixed in an opening 51a formed in a container 51 so that a nozzle 52a is held in the container 51. A cleaning liquid is jetted from plural cleaning liquid nozzles 53a and 53b toward the applying nozzle 52a. 
In the nozzle cleaning apparatus of JP5-309309A, plural (at least two) cleaning liquid nozzles 53a and 53b are required to thoroughly clean the coating nozzle 52a. Further, precise positioning of the coating nozzle 52a is required to allow the cleaning liquid jetted from the cleaning liquid nozzles 53a and 53b to appropriately collide with the coating nozzle 52a. Thus, it is necessary to make the nozzle cleaning apparatus with high precision, which results in an increased apparatus cost.